Looking at specs on the Klipsch website, Fortes go down to 32hz while Chorus II's only go down to 39hz. How can that be? See here:
Forte specs
Chorus II specs
Forte specs
Chorus II specs
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Forte vs. Chorus II
- Thread starter rtomas
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Not that I believe either claim.
Since the Hoosier Garage Door King took over the company has been prone to "Hoffman Creep"; claimed sensitivity going up while claimed f3 goes down. I think ole PWK had a word for that.
I should just post the measurements, but my Chorus II's perform as advertised...both in frequency response and sensitivity.
I've never measured the Forte, but after listening to them a few times it is readily apparent that they dig lower and have a lower sensitivity.
Can you provide any specific examples where the advertised specs are not factual?
I've never measured the Forte, but after listening to them a few times it is readily apparent that they dig lower and have a lower sensitivity.
Can you provide any specific examples where the advertised specs are not factual?
silversport
Super Member
those numbers Dr. Who posted are the same that have been listed since these speakers came out...didn't PWK design the Quartet/Forte' II/Chorus II line???...if you don't like Fred, what did he have to do with these "extended Heritage" speakers???
Bill
Bill
No, but I'll provide some manufacturer's claims which should stimulate some thought, especially in a student at one of the world's top engineering schools.
Heresy II----sealed box, 97db f3 at 63hz
Heresy III---sealed box, 99db f3 at 58hz
Cornwall II---vented box, 98.5db, f3 at 38hz
Cornwall III--vented box, 102db, f3 at34hz
Box sizes are unchanged.
This is fishy. Tell me how this can be. You know Hoffman's Iron Law.
dnewma04
The Healer
Tom, I've noticed the same thing in the past with the specs and was curious about the posted specs. Fishy is a good term.
Couple of possibilities off the top of my head. perhaps the published sensivitity is referenced at 1khz and the F3 is based purely on the woofers referenced sensitivity. In other words, there could be a shelf in the response where the F3 at the referenced 1khz sensitivity might actually be 2-300hz. So instead of posting that, they are going with a published F3 against the woofer itself? But, in any case, misleading advertising would be an appropriate description of what you are seeing. As the published specs, by themselves, would be impossible without further explanation. Should have some asterisks...
Couple of possibilities off the top of my head. perhaps the published sensivitity is referenced at 1khz and the F3 is based purely on the woofers referenced sensitivity. In other words, there could be a shelf in the response where the F3 at the referenced 1khz sensitivity might actually be 2-300hz. So instead of posting that, they are going with a published F3 against the woofer itself? But, in any case, misleading advertising would be an appropriate description of what you are seeing. As the published specs, by themselves, would be impossible without further explanation. Should have some asterisks...
Hoffman's Iron Law holds true for a specific motor strength...put in a bigger magnet, or a better pole piece, or a more linear suspension to allow for a smaller VC gap and you're going to get more output in the same enclosure. There's lots of ways to increase the Bl.
Also, the tuning on the Cornwall III was changed and the driver moved to reduce the effects of standing waves inside the enclosure. The Heresy III is using a totally new woofer. Both are using a new tweeter and squawker too. I believe it's a new version of the K-33 too.
On top of all of this, the whole industry has been measuring sensitivity slightly different than it did 30 years ago. Like using 2.83V instead of a real 1W, or always quoting the 1/8 space performance. Although this will tend towards higher values, it's going to yield more comparable results. Also, a flatter frequency response means the +-3dB window can extend lower in frequency - if the response was ruler flat, then your low frequency limit could be advertised as low as 6dB below the rest of the spectrum. You'll note that it is NOT advertised as the "F3", which has a very defined point. If you're going to complain about this, then take a look at the entire industry that is doing the same (except the rest of the industry is using the 10dB down point...).
Btw, you mentioned PWK...he was a fan of higher efficiency, not higher sensitivity. Higher sensitivity doesn't necessarily mean the acoustical efficiency is higher. For example, the Klipsch folded bass horns have better acoustical efficiency than the direct radiator systems running at about the same sensitivity. Another great example are electrostatics, which take a crap load of power to drive, but their acoustical efficiency is really high (in fact, it competes with horns).
Anyways, ignore all the nonsense theory...have you actually measured and shown something not coinciding with the specs? All the really matters is that the speakers perform as advertised. Somehow I have a feeling that they will measure fine - and if I get a chance perhaps I'll make that measurement and share it. But then what? You still gonna slander Fred?
Also, the tuning on the Cornwall III was changed and the driver moved to reduce the effects of standing waves inside the enclosure. The Heresy III is using a totally new woofer. Both are using a new tweeter and squawker too. I believe it's a new version of the K-33 too.
On top of all of this, the whole industry has been measuring sensitivity slightly different than it did 30 years ago. Like using 2.83V instead of a real 1W, or always quoting the 1/8 space performance. Although this will tend towards higher values, it's going to yield more comparable results. Also, a flatter frequency response means the +-3dB window can extend lower in frequency - if the response was ruler flat, then your low frequency limit could be advertised as low as 6dB below the rest of the spectrum. You'll note that it is NOT advertised as the "F3", which has a very defined point. If you're going to complain about this, then take a look at the entire industry that is doing the same (except the rest of the industry is using the 10dB down point...).
Btw, you mentioned PWK...he was a fan of higher efficiency, not higher sensitivity. Higher sensitivity doesn't necessarily mean the acoustical efficiency is higher. For example, the Klipsch folded bass horns have better acoustical efficiency than the direct radiator systems running at about the same sensitivity. Another great example are electrostatics, which take a crap load of power to drive, but their acoustical efficiency is really high (in fact, it competes with horns).
Anyways, ignore all the nonsense theory...have you actually measured and shown something not coinciding with the specs? All the really matters is that the speakers perform as advertised. Somehow I have a feeling that they will measure fine - and if I get a chance perhaps I'll make that measurement and share it. But then what? You still gonna slander Fred?
dnewma04
The Healer
So Hoffman's Iron Law is more of a Hoffman's Elastic Law is what you are saying? I'm sorry, I haven't found this to be the case, and won't buy an argument that it is. It's non-debatable.
Of course, 2.83v or 1w have been used interchangeably. Has Klipsch changed their measuring methods through the years?
I guess my issue is when specs are published, the methodology should probably also be posted to avoid erroneous looking data. I don't have anything against Klipsch anymore than other companies, but as Tom pointed out, there are discrepancies within the same enclosure sizes. Most other companies don't make these differences so convenient to see because enclosure sizes change often along with models.
Of course, 2.83v or 1w have been used interchangeably. Has Klipsch changed their measuring methods through the years?
I guess my issue is when specs are published, the methodology should probably also be posted to avoid erroneous looking data. I don't have anything against Klipsch anymore than other companies, but as Tom pointed out, there are discrepancies within the same enclosure sizes. Most other companies don't make these differences so convenient to see because enclosure sizes change often along with models.
"Hoffman's Iron Law holds true for a specific motor strength...put in a bigger magnet, or a better pole piece, or a more linear suspension to allow for a smaller VC gap and you're going to get more output in the same enclosure."
More output above F3, which should go higher, not lower.
More output above F3, which should go higher, not lower.
dnewma04
The Healer
Just for shits and giggles, lets think about what the proposed changes you mention would make.
Bigger magnet would lower Qes which raises Fs.
More linear suspension would lower Qms which raises Fs.
Modifying a pole piece for a tighter gap would increase BL and make the suspension more linear which would lower Qes and Qms which both raise Fs.
Ah yes, Hoffmans Iron Law at work.
Bigger magnet would lower Qes which raises Fs.
More linear suspension would lower Qms which raises Fs.
Modifying a pole piece for a tighter gap would increase BL and make the suspension more linear which would lower Qes and Qms which both raise Fs.
Ah yes, Hoffmans Iron Law at work.
Theory is nonsense? An interesting POV. I fail to see how questioning the claims of a business is slander, it's done every day and doing so is an indication of experience.
You take the measurements, then we'll see. Actually with room gain I can see them hitting the target. I modeled the 102db GPA 515LF, in an 8.3 cubic foot box aligned maximally flat it F3ed at 40hz, not bad. Makes me wonder if I screwed up.
Whoa! DIdn't know what I was getting into when I asked my question. But I guess I learned something: Hoffman's Iron Law = trade-off of three parameters given all else equal. But who know if all else is equal.
So here's my issue. I have a pair of Forte's and I love them. But I might have the opportunity to acquire some Chorus II's for cheap. I remember liking them when I listened to them back when they were new in the stores. But I honestly don't remember them well enough to say for sure that they will sound better than my Forte's enough to warrant the cost. The specs would seem to imply they won't since I'd expect them to accel in the bass department but that's where the specs say the Forte's have the advantage. Opinions?
So here's my issue. I have a pair of Forte's and I love them. But I might have the opportunity to acquire some Chorus II's for cheap. I remember liking them when I listened to them back when they were new in the stores. But I honestly don't remember them well enough to say for sure that they will sound better than my Forte's enough to warrant the cost. The specs would seem to imply they won't since I'd expect them to accel in the bass department but that's where the specs say the Forte's have the advantage. Opinions?
dnewma04
The Healer
"All else being equal" has nothing to do with Hoffman's Iron law. 
As far as the comparison between the two models, I think there a great deal of very satisfied listeners with both models. My advice would be to aquire the cheap set, listen and compare, stack them for a little while like any good AKer would do, and then sell off the one you don't want, maybe for the same good deal you got, to another AK member.
As far as the comparison between the two models, I think there a great deal of very satisfied listeners with both models. My advice would be to aquire the cheap set, listen and compare, stack them for a little while like any good AKer would do, and then sell off the one you don't want, maybe for the same good deal you got, to another AK member.
A bigger magnet and tighter gap only increase the B-field at the voice coil. You can keep the Bl the same by using fewer windings...
As far as linear suspension, I was referring to the rocking of the diaphragm as a limit on gap size. With better surround materials and manufacturing tolerances, there are less suspension losses and a looser suspension can be used in a tighter gap.
For what it's worth, the original K-33 was nowhere near optimized for the Cornwall cabinet. In fact, the very earliest drivers had an Fs below 20Hz because PWK originally felt that it was beneficial in the Khorn. I think in the Cornwall II it was pushed up to around ~30Hz and in the Cornwall III, I think it's pushing 40Hz...
Heck, just compare the original Cornwalls to the Chorus II...they share the same bandwidth, but the Cornwall I and II have larger cabinets but less sensitivity. How else would you account for the differences? I might mention that the magnet on the K-48 is at least twice as big (or 4x the really early K-33's). If the Chorus II has no problems achieving 101dB, then why can't the Cornwall III do the same in a bigger enclosure?
I didn't mean to say that theory is nonsense, but theory doesn't matter when you have the real world telling you something different.
I also agree that the testing methods should be part of a posted spec...
2DualsNotEnough
Addicted Member
My buddy in the air force had a set of Fortes,and I have a set of Chorus IIs,and I think the sound is similar.I think the Chorus IIs throw a larger soundstage,but I dont think either speaker is a slouch.Hey,Rtomas,did we talk this afternoon?:thmbsp:
Jimmy
Jimmy
Do you have Forte I or II?
My impressions from listening to the Forte II and the Chorus II were that the Forte was voiced better and the bass definitely dug lower. The Chorus has relentlessly flat bass and sounds a lot cleaner. Sometimes the Chorus II sounds a bit pinched in the mids, which I think might be happening with the Forte too, but it's not as noticeable since the bass is tipped up a bit more. The Chorus definitely sounds a lot larger and can handle louder listening levels better than the Forte.
In fact, it seems like the Chorus wakes up a bit with increased levels. There are some interesting measurements over at Home Theater Shack that seem to imply that passive radiator efficiency increases with increased SPL (kinda like passives have a dead spot when sitting at rest). I need to measure it, but that might coincide with a perceived increase in bass with louder listening levels (that is more than just the effects of fletcher-munson equal loudness).
2DualsNotEnough
Addicted Member
I totally agree with you about increased perceived bass at higher listening levels.It seems like the stage is more narrow,the bass more reticent until you hit a certain decibel level,then they open up a lot.
Jimmy
Jimmy
I have Forte I's. They're 4 ohm if that makes a difference. In fact, that was going to be my next questions. It seems like the Forte I came in both 4 ohm and 8 ohm varieties. And I think I've noticed that the 4 ohm version had the round terminal cup while the 8 ohm version had the rectangular cup. I'm pretty sure the Forte II's were all 8 ohms. Does this all sound correct?
GrantLee63
New Member
I have a set of the Forte II's that I purchased in 1990 and they have the rectangular cup and are 8 ohms.
